1. Field of the Invention
The invention relates to a pulley hub for joining with a bottom wall of a sheet metal pulley for mounting the pulley on a shaft. More particularly, the invention relates to a pulley hub which is formed inexpensively of sintered powder metal in a single piece, and which provides a pair of hub pulling flanges thereon.
2. Description of the Prior Art
Many pulley hubs are formed from tubular steel stock which is cut to predetermined axial lengths with the various hub pulling flanges and pulley cup mounting grooves being machined or milled therein. These hub constructions are satisfactory for their intended applications, but the machining required to form such flanges and grooves increase considerably the cost of the hub. Also greater metal thickness is required in the area of the hub at the point of pulley attachment for the formation of such removal tabs and grooves. The removal of this metal by machining to form the required grooves and lugs results in metal scrap waste.
Machining generally is required to form a groove or recess in the hub body to provide a projection on one end of the hub for gripping by a hub puller for removing the hub and connected pulley from a shaft, should replacement be required. Such machining also is required to form flanges, recesses, indentations, etc., for receiving and mounting a sheet metal pulley which is secured thereon by welding, brazing or the like.
Recent years have seen advancements in powder metallurgy and the subsequent production of numerous products including hubs from powder metal by pressing and sintering predetermined quantities and mixtures of such powder metal. Examples of various articles formed from metal powder and methods of producing such articles are illustrated in U.S. Pat. Nos. 2,561,583, 3,260,596, 3,391,444, 3,719,479 and 3,720,512.
Problems, however, have been encountered in attempting to form hubs for pulleys having annular flanges and grooves formed therein by powder metallurgy methods. It is difficult to form an annular groove in the hub body which forms an annular pulling flange due to the difficulty of press forming such an exterior annular groove in the green pressed hub compacts prior to sintering in known press molding equipment.
This problem was eliminated by the two-piece sintered pulley hub construction and method of making the same, disclosed in application Ser. No. 680,427, filed Apr. 26, 1976, which is assigned to the same assignee as this application. Such a two-piece hub construction forms the desired annular pulling groove therein when the two separately molded green compacts are assembled by a unique arrangement of flanges and shoulders formed on the two components. This two-piece arrangement eliminates the forming of an annular groove in a one-piece sintered member which is difficult. This two-piece pulley hub provides a satisfactory solution to a problem, but requires molding of two separate components which then are telescopically joined to form a single member prior to sintering. This procedure and construction increases the number of steps and manipulations required in forming the final pulley hub which increases the final hub cost.
No known pulley hub construction of which I am aware eliminates these difficulties by providing a one-piece sintered powder metal pulley hub structure having a pair of outwardly radially extending flanges or lugs formed thereon, thereby eliminating the formation of any annular groove in the hub body.